Motor-starter.



No. 759,150. PATENTED' MAY 3, 1904. W. BAXTER, JR.

MOTOR STARTER.

APPLIOATIONIILED r113. 9,-1904.

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No. 759,150. BATENTED MAY 3, 1904.

W. BAXTBR, JR.

Y MOTOR STARTER.

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Patented May 3, 1904.

WVILLIAM BAXTER,'JR., OF JERSEY CITY, NEW JERSEY.

MOTOR-STARTER.

SPECIFICATION forming part of Letters Patent No. 759,150, dated May 3,1904.

Application filed February 9, 1904. Serial No. 192,823. (N model.)

To all whom zit may concern: 7

Be it known that I, WILLIAM BAXTER, Jr.,

a citizen of the United States, and a resident of Jersey City, in thecounty of Hudson and State of New Jersey, have invented a newand usefulImprovement in Automatic Motor- Starters, of which the following is aspecification.

This invention relates to automatic motorstarters, and has for itsobject the obviating of certain defects in such devices as now made.

The construction and operation of my invention will be fully understoodfrom the accompanying drawings, in which Figure 1 is a diagrammaticrepresentation of my invention in the preferred form. Figs. 2 and 3 aremodifications presented for the purpose of more fully illustrating thescope of my invention. 1

Like reference-marks indicate like parts in all the drawings.

The motor is represented by A and M, the former being the armatureandthe latter the shunt field-coil. At S is shown a two-pole switch toconnect the motor and starter with the supply-circuit P N, Fig. 1.

The motor-starter consists of a main switch B, a rheostat-switch (J, arheostatR R with contacts V V, and acompound-coil magnet, whosefunctions willbe presently explained. l/Vith theswitches B and C in theposition shownin Fig. 1 the current from P, passes. to wire 1,

thence through A to wire 2,through the magnet-coil Y towire 3 and tocontact V, rheostatswitch C, main switch B, wire l,andtosupplycircuitline N. From Wire 1 acurrent is shunted through wire5-.to M, thence. to wire 6 and throughmagnet coil-X to wire 7, andthence through the rheostat R R to switch (Land thus to main-line wireN.

In automatic motor-starters as now made the .rheostat-switch C is heldin the running position, asshown in the drawings, by a retaining-magnetthe energizing-coil of whichis connected in series with the field M justas X is connected. in the drawings. So long as, the currentflows'through this. magnet, C is retained in the running position; butif thecurrent fails G can swing counter-clockwise to the stop oropen-circuit posltlon. This arrangement protects the motor frominjury ifthe circuit through M is broken in anyway; but at the same time itseriously damages the contacts Vof the motor-starter, for if C swingsback over these contacts after the circuit through .M is broken thecurrent passing through from C to the contacts V will be very great, andas a result the sparking between these contact-points will lac-excessiveand will so roughen up the surface as to make it probable that in futurebackward movements of. C it will be caught-at some intermediate pointand be prevented from swinging all the way to the open position. I-naddition to the retaming-magnet to hold C in the running positionmotor-starters as now made are provided with another magnet whoseenergizingcoil is connected in series with the motorarmature. open thecircuit through the motor if the current becomes too strong from anycause. This magnet acts in some cases upon a separate switch and issimply a circuit -breaker. In other cases it acts to shortcircuit themagnetizing-coil of the retaining-magnet that holds C in the runningposition, so as to permit this switch to swing to the open position,andthus break the motor-circuit. With either construction the magnetacts effectually to protect the motor from overloads; but when itshort-circuits the retaining-magnet coil it permits the rheostat-switchto swing over the contacts to the stop position when a strong current ispassing from this switch to the contacts, and this, as alreadyexplained, is decidedly objectionable. To insure perfect operation ofthe rheostat-lever C, it is necessary that the contacts Vandthe end of Cthat slides over them be kept as smooth as possible, so that there maybe no danger of the switch sticking at an intermediate point whenever ithas to swing back to the stop position. To

. maintain these surfaces smooth, it is necessary that the operation ofthe starter be such that C cannot swing back to the stop position when acurrent is passing through it, for if a current passes at such timesthere will be sparking between C and the contacts V, and the edges ofboth parts will be burned and roughened up.

In my arrangement of motor-starter it will be seen that the magnet D Eis energized by lessB is in the position shown and C rests on the coilsX and Y, the former being connected in series with the shunt field-coilM of the motor and the latter being connected in series with thearmature A of the motor. These two coils assist each other in energizingthe magnet. If the motor is running, the switches B and (I will be inthe position shown, and if the circuit through M and X is broken in anyway the rheostat-switch C will not swing back over the contacts V,because the magnetizing force of coil Y will keep up the strength of themagnet and thus hold the armature F mounted uponC. If the line-currentfails, both coils X and Y will become deenergized, and then the magnetwill not hold armature F. Hence the rheostat-switch (I will be free toswing back to the stop position; but in this case there will be nocurrent passing through 0, since there will be no current in the mainline. The main switch B is held in the closed position by thetogglejoint 12 13, one end of which is pivoted to a stationary supportand the other end to arm 11 of B. The two switches B and C are mountedupon acommon stud 20 and are drawn toward each other, as indicated bythe arrows a b, by the tension of spring 17, the end 18 of which engageswith B, while the other end, 18, engages with C. If the motor is runningwith the switches B and C in the position shown and the line-currentdies out, C will swing around until it strikes stop 10 on B, and thusthe motor-circuit will be open, as C will not be in contact with any oneof the contacts V. 1f the motor is running and the current through thearmature becomes excessive, the magnetizing force of coil Y willincrease until the magnet will be able to draw up 16, and then thetrip-rod let will strike 13 and trip the toggle-joint, thus permittingthe tension of spring 17 to draw B upward and open the motor-circuit. Ifwhile the motor is running the circuit through the field-coil M breaks,the rheostat-switch C will be held in the running position; but as soonas the motor-field weakens the armature-current will increase, and whenit becomes strong enough the magnetizing force of Y will be sufficientto enable the magnet to lift 16, and thus trip the toggle-joint andpermit B to swing upward and open the circuit.

From the foregoing it will be seen that when the motor is running andthe motorstarter switches are in the position shown in the drawings ifthe main current dies out C will swing counter-clockwise until itreaches B; but if the current through the armature becomes excessive orif the field-coil circuit breaks (I will retain its position and B willswing up toward it, and thus open the motorcircuit. when the motor isstopped, the switches B and C may be in any position between that of Band that of C; but they will be both together and the motor-circuit willbe open, as this circuit cannot be closed unone of the contacts V. Tostart the motor, the operator takes hold of the handle T on (J and movesit counter-clockwise until B reaches the position in which it is shown,and then the toggle 12 13 will become locked and will hold B until it isreleased by the action of the triprod 1 1. Having set B, the operatorswings C clockwise gradually over contacts V to the position in which itis shown, and it will then be held in this position by theretaining-magnet. To stop the motor, the operator lifts 16, so as totrip the toggle 12 13 and permit B to swing upward.

The essential feature of my invention is the compound coil-magnet l) E,which acts to hold the rheostat-switch C in the running position underall conditions except when the mainline current dies out and which actsto open the switch B whenever the current through the armature becomesexcessive from any cause.

Motor-starters are now made in which the coil Y energizes a magnet thatacts to open switch B and the coil X energizes a retaining-magnet thatholds switch C; but these devices fail to accomplish the result forwhich my arrangement is intended, because if the current through thefield-coil M fails the magnetizing force of X reduces to zero, andswitch 0 will swing over the contacts V while \a strong current ispassing, owing to the fact that the magnetism of the retaining-magnetwill die out sooner than that of the motorfield on account of the latterbeing so much larger. Hence C will be released before thearmature-current rises to a strength suflicient to cause coil Y to act.

I have shown a toggle-joint 12 13 and trip rodl t for holding andreleasing switch B; but this is simply a preferred construction and canbe replaced by any of the catch and trip devices commonly used withcircuitbreakers without departing in any way from my invention. I havealso shown a spring on 14:, held between the stationary guide 1!) andthe adjusting-nuts 15, by means of which the tension opposing thetractive force of the magnet I) E is balanced, so as to adjust thedevice to trip with any desired strength of current; but these detailscan also be varied in any desired manner. The coil X is shown connectedin series with the motor-field M; but it can be located in a separatecircuit that is in parallel with the motor armature, as shown in Fig. 2,without changing the operation of the starter. "ith this connection ifthe line-current fails coil X will be deenergized just as it would be ifconnected in sc ries with M. 1f the circuit through M should break,theincrease of current through Y would act, as already explained, torelease B. The

placing of X in series with M is desirable, because it can be made ofcomparative] y large wire and a small number of turns, as the fieldcoilM balances nearly all the electromotive force of the supply-circuit. IfX is connected in an independent circuit, as shown in Fig. 2, it willhave to balance the whole electromotive force of the supply-circuit, andon that account will have to be made of very fine wire and many turns,and this is objectionable, not only on account of the greater cost ofconstruction, but also on account of the greater liability of breakingthe wire.

In Fig. 1 the switches 13 and G are arranged to swing around the samecenter; but this construction is not a necessary feature of myinvention. They may be mounted on independent studs, as shown in Fig. 3,or may be made in accordance with any of the designs of motor-starterscommonly used, as is illustrated clearly in Fig. 2, providing they arearranged so as to be controlled by a compound eoil-magnetin the mannerherein described.

In Fig. 1 coil Y is shown connected in the motor-armature circuit; butit can be readily seen that it can be connected in wire 1 or in wire 1above point 0, as in Fig. 2, without changing its action in any way. Infact, the only effect of this change would be to slightly increase thecurrent flowing through the coil. I therefore claim the connecting ofthe coil in either of these positions.

In Fig. 2 the rheostat-switch C moves in a straight line, being guidedby guide 23, and the force of gravity is utilized to return this switch,as well as the main switch and the lever 16, to the stop position. Bymeans of a weight 22 the force acting to oppose the pull of the magneton lever 16 can be varied.

in Fig. 3 the two switches and lever 16 are retracted by the tension ofsprings marked 21 21 21". The circles 24 are stops to limit the movementof the switches and of lever 16.

The coil X can be dispensed with without interfering with the action ofthe retainingmagnet, provided the motor is run fairly well loaded at alltimes; but if the load is greatly reduced the coil Y alone will notdevelop sufiicient magnetism to retain the rheostat switch C in therunning position unless the magnet is made undesirably large. From thisit will be seen that the most important oflice of coil X is to developsuflicientmagnetism to retain switch 0 in therunning position when themotor is running free or whenever the load is so light that the currentpassing through Y is not sufficient to enable this coil alone to developthe magnetism required to hold G in the running position. In the severaldrawings it will be noticed that the retaining-magnet is arranged sothat the poles at one end act on one switch and the poles at the otherend act on the other switch.

Having thus described my invention, what I claim as new therein, anddesire to secure by Letters Patent, is the following:

1. The combination in amotor-starter, of a main switch,arheOstat-switch, means to throw these switches to the stop position,means to hold the main switch in the running position, a magnet adaptedto hold the rheostat switch in the running position and to release themain switch when the motor-current becomes too strong, and to releasethe rheostat switch whenever the motor-current dies out.

2. The combination in a motor-starter of a main switch arheostat-switch, means acting to draw both switches away from therunning position, means for holding the main switch in the runningposition, a magnet connected in the motor-circuit and adapted to actindependently on both switches, holding the rheostat-switch in therunning position and releasing the main switch whenever themotor-current becomes too strong, but without releasing therheostat-switch.

3. In a motor-starter the combination of a main switch provided withmeans for holding it in the running position and means for releasingsaid holding means, a rheostat-switch, means acting to draw each switchaway from the running position, a magnet connected in the motor-circuitand having poles at one end to hold the rheostat-switch in the runningposition, and poles at the other end that actuate the means forreleasing the holding means of the main switch, this magnet beingconstructed to release the main switch whenever the motorcur rentbecomes too strong, without releasing the rheostat-switch, and torelease the rheostat-switch whenever the motor-current becomes too weak.

4;. A motor-starter provided with a switch to open the motor-circuit, aswitch to cut out the starting resistance, a compound coil-magnetadapted to openthe first-named switch without moving the other switchwhenever the current through the motor-armature becomes excessive, andto hold the second-named switch in the running position so long ascurrent flows through the motor.

5. A motor-starter provided with a main switch and a rheostat-switchboth of which are controlled independently by a magnet that is energizedby two coils, one coil being connected in series with the motor-armaturethe other coil being connected in shunt relation to the motor-armature.

6. A motor-starter provided with a main switch, a rheostat-switch and acompound coil-magnet to control these switches independently, one of thecoils of the magnet being connected inseries with the motor-armature,the other coil being connected in series with the shunt field-coil ofthe motor.

7. A motor-starter provided with a switch to close the motor-circuit,another switch to cut the starting resistance out of thearmature-circuit, a compound coil-magnet to control both switchesindependently, one of the magnet-coils being traversed by the mainmotor-current, the other coil being traversed by a current shuntedaround the motor-armature.

8. In a motor-starter the combination of a main switch means for lookingit in the closed position, means to throw it to the open position, arheostat-switch adapted to be held in the running position by a magnet,means for throwing this switch to the stop position, a magnet energizedby two coils one of which is connected in series with the mainmotorcircuit the other being connected in a circuit that shunts themotor-armature, this magnet being adapted to hold the rheostat-switch inthe running position and to unlock the main switch substantially in themanner described.

9. In a motor-starter, amain switch, a rheostat-switch, a toggle-jointlock to hold the main switch closed, means for holding therheostat-switch in the running position means for throwing both switchesto the open position, means for tripping the toggle-joint lock, acompound coil-magnet connected in the circuit in the manner describedand adapted to actuate the tripping device and to control the means thathold the rheostat-switch in the running position.

10. In a motor-starter, a main switch and means for holding it in theclosed position, a rheostat-switch carrying an armature, means forthrowing either or both switches to the stop position, means forreleasing the main switch, a magnet adapted to attract therheostat-switch armature and to actuate mainswitch-releasing device,this magnet being energized by coils connected in the motor-circuit onein series and one in parallel with the motor-armature.

11. In a motor-starter arranged substantially as described, a compoundcoil-magnet having poles at both ends, the poles at one end acting toretain the rheostat-switch in the running position, the poles at theother end acting to move the tripping mechanism that releases the mainswitch.

12. In a motor-starter arranged substantially in the manner described, acompound coil-magnet connected in the motor-circuit in the mannerdescribed, one of its ends attracting an armature mounted upon therheostatswitch but electrically insulated therefrom, the other endacting upon the tripping device that releases the main switch.

13. In a motor-starter arranged substan tially as described, with alocking device for the main switch, an unlocking device for opening thelocking device, a compound coil-magnet connected in the motor-circuit inthe manner described, to actuate the unlocking device, means to opposethe action of the magnet upon the unlocking device and means to vary themagnitude of this opposition.

14. In combination with a motor-starter having a rheostat-switch and amain switch and a locking means for said main switch; the trip-rod 1 1for releasing said locking means, the guide 19 for said rod, theactuating armature'lever 16 for said rod, and the compound coilmagnet DE, arranged to act on said armature-lever and also directly controllingthe rheostat.

15. In combination with a motor-starter arranged in a mannersubstantially as described with a rheostat-switch and a main switch; arod 14: arranged to release the main switch, guide 19 for said rod,lever 16 controlling said rod, a magnet l) E, in controllingrelation tothe rheostat-switch and to the lever 16, and means to resist theattraction of the magnet for lever 16.

16. In combination with a motor-starterarranged substantially asdescribed with a rheostat-switch and a main switch; a rod 1 1 adapted torelease the main switch, guide 19 for said rod, lever 16 connected withsaid rod, magnet l) E controlling the rheostat-switch and said lever, aspring mounted on rod 1% to resist the attraction of the magnet for saidlever, and means for adjusting the tension of this spring.

17. In a motor-starter arranged substan tially as described, thecombination of switch B provided with an arm 11, the toggle 12 13, red14:, guide 19, lever 16, magnet I) E, a re sisting force to oppose theattraction of the magnet for lever 16, and means for varying themagnitude of this opposing force.

18. In a motor-starter arranged substantially as described, aretaining-magnet with its iron parts curved at the upper end andterminating in pole-surfaces substantially parallel with therheostat-switch when the latter is in the running position.

19. In a motor-starter, the combination of the switches B and C, meansfor throwing them to the stop position, the rheostat R and contacts V,the magnet I E energized by coils X Y, the locking device 12 13, the rod1 1, lever 16, guide 19, the spring mounted on 11 and the adjustingnuts15.

The foregoing specification signed this 6th day of February, 190%1.

IVILLIAM BAXTER, Jn.

In presence of Joim H. PHAIR, STEPHEN H. OLIN.

